1. Field of the Invention
This invention relates to a single-reel type tape cartridge for use with magnetic recording-reproducing apparatus (hereinafter called a xe2x80x9crecorderxe2x80x9d).
2. Prior Art
Japanese Patent Application Kokai No. 63-251983 discloses a single-reel type tape cartridge having a brake lock which applies the brake on the tape reel and releases it by upward and downward motion within a hub on which the tape is wound.
FIG. 5 is an exploded view of a single-reel type cartridge of the prior art and FIG. 6 is a cross sectional view showing essential parts of the cartridge. For easier reference the components are shown upside down. The cartridge comprises a housing composed of an upper casing 1 and a lower casing 2, and a single tape reel 3 on which a length of tape 14 is wound and which is turnably held within the housing.
Upper and lower casings 1, 2 are formed, respectively, with cutouts 12, 22 which are joined to provide an opening into which a leader block 9 is inserted so as to be drawn out by a drive member on the part of a recorder.
Tape reel 3 consists integrally of a hub 32 formed in one piece with a lower flange 33. It is driven for rotation by a drive of a recorder that is inserted into the opening 20 of lower casing 2.
Hub 32 has a tooth-like part formed on its inner surface to be in mesh with a brake lock 5 so as to prevent unwanted turning of tape reel 3 when the latter is not in use.
Brake lock 5 has teeth 51 formed on its underside in mesh with the corresponding part of hub 32. Brake lock 5 is normally urged in the braking position by a brake spring 4.
A follower projection 52 of brake lock 5 has a recess 73 which slidably engages with a guide 13 formed on the inner surface of upper casing 1, allowing brake lock 5 to move up and down positively between a lower braking position and an upper brake release position.
A brake release projection 63 formed on the underside of brake lock 5 fits in a center hole 43 at the bottom of hub 32, and as soon as the cartridge is loaded in a recorder, brake release projection 63 is lifted with an attendant upward movement of brake lock 5 out of engagement with tape reel 3, setting the reel free to turn.
The beginning of tape 14 is wound round a pin member 8, which in turn is fixedly fitted in a pin-receiving groove of a leader block 18. When the cartridge is loaded in a recorder, leader block 18 is caught by a draw-out member that comes out of the recorder into an engaging recess 19 of the block. It is then drawn out, led along the tape path inside the recorder up to a takeup reel, and is eventually held within a recess formed in the periphery of the recorder""s take-up reel.
In the cartridge of the prior art, the brake on the hub is released as brake lock 5 is lifted with its brake release projection 63 pressed by a brake release member of a recorder. When the center of either projection 63 or the brake release member of a recorder is off the center of the other (a situation that can result from dimensional errors of the products), smooth release of the brake is sometimes impossible because the brake lock fails to move straightly upward or because the outer periphery of brake lock 5 catches a sloped rib 72 (FIG. 6) that centers brake lock 5 with respect to hub 32.
It might seem possible then to accomplish positive release of the brake by the interposition of a brake release plate between the brake release member of a recorder and brake lock 5 on the part of the cartridge. However, the idea has not yet materialized in a perfect solution.
It is therefore an object of the present invention to provide a single-reel type tape cartridge capable of releasing the brake on the hub reliably and positively.
In the above case the brake release plate would turn in contact with the brake button while the tape reel is turning. If the two parts are not in good sliding contact, they would hamper smooth turning of the tape reel.
It is therefore another object of the invention to provide a single-reel type tape cartridge capable of ensuring smooth turning of the tape reel.
The present invention realizes the above objects by providing a tape cartridge wherein a single tape reel on which a length of tape is wound is turnably held within a housing consisting of an upper casing and a lower casing, the lower casing having an opening through which a drive shaft of a recorder is to be inserted, the tape reel having a hub which is open at top and is closed at the bottom with a wall, the bottom wall of the hub having holes for engagement with a brake release plate, a metal disk is attached to the outer surface of the underside of said hub and teeth are formed on the outer surface around the metal disk for engagement with the drive shaft of a recorder, teeth to engage a brake lock are formed on the inner bottom surface of the bottom wall of the hub, a brake release plate is mounted in the hub with legs fitted in the holes of the latter, a brake lock rests on the brake release plate, the brake lock having brake teeth formed on the periphery of the underside to be in mesh with the teeth of the hub and having a follower projection on the upper surface which is adapted to be guided by a guide projection formed in the upper casing so as to be movable upward and downward but not turnable, and a spring member is provided between the brake lock and upper casing to urge the brake lock in the braking position, characterized in that
said brake lock is formed with a dent (or lug) with a spherical end in the center of its underside, and the brake release plate is formed with a corresponding lug (or dent) with a spherical end on its upper surface.
Here even more accurate reel centering is made possible by increasing the radius of curvature R of the dent to a value greater than the radius of curvature r of the end of the lug.
The invention also provides a tape cartridge wherein a single tape reel on which a length of tape is wound is turnably held within a housing consisting of an upper casing and a lower casing, the lower casing having an opening through which a drive shaft of a recorder is to be inserted, the tape reel having a hub which is open at top and is closed at the bottom with a wall, the inner bottom wall of the hub having holes for engagement with a brake release plate, a metal disk is attached to the outer surface of the underside of said hub and teeth are formed on the outer surface around the metal disk for engagement with the drive shaft of a recorder, teeth to engage a brake lock are formed on the inner bottom surface of the hub, a brake release plate is mounted in the hub with legs fitted in the holes of the latter, a brake lock rests on the brake release plate, the brake lock having brake teeth formed on the periphery of the underside to be in mesh with the teeth of the hub and having a follower projection on the upper surface which is adapted to be guided by a guide projection formed in the upper casing so as to be movable upward and downward but not turnable, and a spring member is provided between the brake lock and upper casing to urge the brake lock in the braking position, characterized in that
a highly slippery sheet member is interposed between the contacting parts of the brake lock and the brake release plate.
Preferably, the brake lock is formed with a dent (or lug) with a spherical end in the center of its underside, and the brake release plate is formed with a corresponding lug (or dent) with a spherical end on its upper side.
Also preferably, reinforcing ribs are provided on the underside of the brake release plate.
According to the invention, a dent (or lug) with a concave or convex surface is formed in the center of a brake lock and a corresponding lug (or dent) with a convex or concave surface is formed on the upper surface of a brake release plate. Thus, even if the brake lock and brake release plate are out of center alignment upon release of the brake, the concave and convex of the two centers remain aligned, performing automatic centering of the tape reel and ensuring stable turning of the reel.
Also, under the invention, the friction between the contacting rake has been released is decreased by the interposition of a highly slippery sheet material, and the turning of the tape reel is made smooth.